SUMMARY/ABSTRACT This competing renewal application represents a translational continuation of our long-standing research on dietary patterns and cardiovascular disease (CVD) that extends to the interconnections between dietary patterns, gut microbes, and metabolomic profiles. The recently released 2015-2020 Dietary Guidelines for Americans recommends three dietary patterns - the Healthy US-Style Eating Pattern, the Healthy Mediterranean-Style Eating Pattern, and the Healthy Vegetarian Eating Pattern. In this project, we will examine the associations between these three recommended dietary patterns and CVD risk in four large prospective US cohorts, with a particular focus on potential racial/ethnic differences. In Aim 1, we will create updated indices for each dietary pattern (Healthy Eating Index [HEI]-2015, Mediterranean Diet Index [MDI], Healthful Plant-based Diet Index [hPDI]), and evaluate potential racial/ethnic differences in their associations with CVD in the Nurses' Health Study (NHS), NHSII, and Health Professionals Follow-up Study (HPFS), including 231,000 non-Hispanic whites, 3,600 African Americans, 3,000 Asians, and 2,400 Hispanics. We will also construct the three diet indices in the Hispanic Community Health Study/Study of Latinos (HCHS/SOL; n=13,000) and evaluate their associations with CVD during 12 years of follow-up. Secondarily, we will examine the associations of these diet indices with CVD in diverse Hispanic groups (Puerto Rican, Mexican, Central/South American, Cuban, and Dominican). In Aim 2, we will evaluate the relationship between adherence to the three dietary patterns and plasma metabolic profiles (including CVD-related candidate metabolites and novel metabolic pathways based on >500 metabolites) in a subsample of 1,100 NHS/HPFS participants and 477 HCHS/SOL participants. In addition, we will identify and characterize gut microbiome markers, via shotgun metagenomic and metatranscriptomic sequencing, that are associated with the three dietary patterns among 621 NHSII/HPFS participants and 400 HCHS/SOL participants who provided or will provide stool samples. In secondary analyses, we will examine associations between the three dietary pattern scores and gut microbial features stratified by Hispanic sub-groups and compare them with non-Hispanic whites. The proposed study, with a unique prospective US Hispanic cohort, will be the first to assess adherence to dietary guidelines in relation to CVD risk in this population. Using state-of-the-art metabolomics and microbiome technologies, this study will also be among the first to explore potential mechanisms through which long-term adherence to recommended dietary patterns influences CVD risk in diverse racial/ethnic groups. Built on well-established long-term cohorts, archived biospecimens, and advanced -omics technology, this competing renewal will advance our understanding of the cardio-metabolic benefits associated with healthy dietary patterns, providing novel insight into the dietary prevention of CVD. !